BIOL 227 EXAM 3 Questions with Complete Solutions 100% Verified| Latest
Update Graded A+
Identify and describe the three connective tissue layers associated with a skeletal muscle.
Epimysium: a dense layer of collagen fibers that surrounds the entire muscle; separates the
muscle from surrounding tissues and organs.
Perimysium: divides skeletal muscle into a series of compartments, each containing a bundle of
muscle fibers called a fascicle
Endomysium: surrounds individual skeletal muscle cells (fibers); loosely connects neighbouring
fibers in a fascicle *these three layers of connective tissue are collected together at the tendon
Describe the structure and function of a tendon and an aponeurosis. A tendon is a
projection of connective tissue beyond the ends of the muscle that attaches to bone.
An aponeurosis is a broad fibrous sheet of connective tissue that connects muscles to adjacent
muscles.
Explain the distribution and function of blood vessels and nerves serving a muscle. Blood
vessels deliver oxygen and nutrients to the muscle fibers, as well as remove waste from the
muscle fibers. Nerves serve to allow muscles to move using motor neurons (voluntary muscles).
Explain how a skeletal muscle fiber becomes multinucleated. skeletal muscle fibers become
multi-nucleated when embryonic cells called myoblasts fuse to form a synctytium, a cell with
many nuclei. the resulting muscle fiber is a large, elongated multi-nucleated cell.
Describe the sarcolemma, T-tubules, sarcoplasmic reticulum, and triad of a skeletal muscle
fiber. Muscle Cell is surrounded by a connective tissue sheath called the endomysium. The
"membrane" of the muscle cell is known as the sarcolemma. At the motor end plates of
neuromuscular junctions, action potentials continue from the axon terminal to the sarcolemma
via acetylcholine. The action potential continues down sarcolemma and into T (transverse)
tubules. Due to a mechanical link between the t tubules and the sarcoplasmic reticulum, action
, potentials traveling down the T tubules cause Voltage gated Calcium channels in the S.R. are
opening calcium channels allowing Ca2+ ions to diffuse into sarcolemma.
Distinguish between thick and thin filaments. The thin filaments contain actin, tropomyosin,
troponins C, I, and T and nebulin. The thick filaments are composed of myosin with the globular
heads forming cross-bridges with thin filaments
Explain the organization of myofibrils, myofilaments, and sarcomeres. myofibrils- Long
cylindrical structures that form 80% of muscle fibers
Myofilaments- bundles of these make up myofibril. *not as long as myofibril. Myofibril bundles
contain 2 types of myofilaments thick and thin
Sarcomeres- the repeating cylindrical units of myofilament within myofibrils
Z- disc are composed of specialized proteins that are positioned perpindicular to myofilamints
and serve as anchors for thin filaments
I Bands- extend from both direction of a Z disc. Ends contain only thin filaments. Appear light
under microsI bands dissappear at high muscle contraction
A Band- central region of sacromere that contain entire thick fillament. appears dark
H Zone- Most central portion of A band
Overlapping myofillaments form light and dark regions which make skeletal muscle striated.
due to size and density differences between thin and thick fill.
List and describe the structures associated with energy production within skeletal muscle fibers.
Mitochondria: for aerobic respiration; muscle fibers contain abundant mitochondria.
Myoglobin: reddish globular protein that binds oxygen when the muscle is at rest and releases
it for use during muscular contractions.
Define a motor unit, and describe its distribution in a muscle and why it varies in size. A
single motor neuron and the muscle fibers it controls. The size of the motor neuron determines
the degree of control. (eyes have little motor neurons b/c it takes greater control to move).
Motor neurons are dispersed throughout a muscle fiber.
Update Graded A+
Identify and describe the three connective tissue layers associated with a skeletal muscle.
Epimysium: a dense layer of collagen fibers that surrounds the entire muscle; separates the
muscle from surrounding tissues and organs.
Perimysium: divides skeletal muscle into a series of compartments, each containing a bundle of
muscle fibers called a fascicle
Endomysium: surrounds individual skeletal muscle cells (fibers); loosely connects neighbouring
fibers in a fascicle *these three layers of connective tissue are collected together at the tendon
Describe the structure and function of a tendon and an aponeurosis. A tendon is a
projection of connective tissue beyond the ends of the muscle that attaches to bone.
An aponeurosis is a broad fibrous sheet of connective tissue that connects muscles to adjacent
muscles.
Explain the distribution and function of blood vessels and nerves serving a muscle. Blood
vessels deliver oxygen and nutrients to the muscle fibers, as well as remove waste from the
muscle fibers. Nerves serve to allow muscles to move using motor neurons (voluntary muscles).
Explain how a skeletal muscle fiber becomes multinucleated. skeletal muscle fibers become
multi-nucleated when embryonic cells called myoblasts fuse to form a synctytium, a cell with
many nuclei. the resulting muscle fiber is a large, elongated multi-nucleated cell.
Describe the sarcolemma, T-tubules, sarcoplasmic reticulum, and triad of a skeletal muscle
fiber. Muscle Cell is surrounded by a connective tissue sheath called the endomysium. The
"membrane" of the muscle cell is known as the sarcolemma. At the motor end plates of
neuromuscular junctions, action potentials continue from the axon terminal to the sarcolemma
via acetylcholine. The action potential continues down sarcolemma and into T (transverse)
tubules. Due to a mechanical link between the t tubules and the sarcoplasmic reticulum, action
, potentials traveling down the T tubules cause Voltage gated Calcium channels in the S.R. are
opening calcium channels allowing Ca2+ ions to diffuse into sarcolemma.
Distinguish between thick and thin filaments. The thin filaments contain actin, tropomyosin,
troponins C, I, and T and nebulin. The thick filaments are composed of myosin with the globular
heads forming cross-bridges with thin filaments
Explain the organization of myofibrils, myofilaments, and sarcomeres. myofibrils- Long
cylindrical structures that form 80% of muscle fibers
Myofilaments- bundles of these make up myofibril. *not as long as myofibril. Myofibril bundles
contain 2 types of myofilaments thick and thin
Sarcomeres- the repeating cylindrical units of myofilament within myofibrils
Z- disc are composed of specialized proteins that are positioned perpindicular to myofilamints
and serve as anchors for thin filaments
I Bands- extend from both direction of a Z disc. Ends contain only thin filaments. Appear light
under microsI bands dissappear at high muscle contraction
A Band- central region of sacromere that contain entire thick fillament. appears dark
H Zone- Most central portion of A band
Overlapping myofillaments form light and dark regions which make skeletal muscle striated.
due to size and density differences between thin and thick fill.
List and describe the structures associated with energy production within skeletal muscle fibers.
Mitochondria: for aerobic respiration; muscle fibers contain abundant mitochondria.
Myoglobin: reddish globular protein that binds oxygen when the muscle is at rest and releases
it for use during muscular contractions.
Define a motor unit, and describe its distribution in a muscle and why it varies in size. A
single motor neuron and the muscle fibers it controls. The size of the motor neuron determines
the degree of control. (eyes have little motor neurons b/c it takes greater control to move).
Motor neurons are dispersed throughout a muscle fiber.
